Interaction between Various Apple Procyanidin and Staphylococcal Enterotoxin A and Their Inhibitory Effects on Toxin Activity.

In this study, we investigated the interaction between apple polyphenols (AP; mainly consisting of procyanidin (PC) from an apple) and staphylococcal enterotoxin A (SEA), and the inhibitory effects of AP on SEA activity. According to the degree of polymerization, in particularly highly polymerized PC (more than pentamer) strongly interacted with SEA. The binding affinity of AP with SEA molecules was determined using Biacore analysis. AP reacted with SEA immobilized on a Biacore sensor chip. After treatment with pepsin and pancreatin, to examine the changes of binding affinity of AP in intragastric conditions, AP maintained interaction with SEA. We examined whether AP inhibits the proliferation and interferon-γ (IFN-γ) production induced by SEA in mouse spleen cells. AP strongly inactivated the proliferation and IFN-γ production induced by SEA. These results suggest that AP, which has a higher degree of polymerization, inactivates stronger biological activity of SEA through interaction with SEA. Our studies are the first to demonstrate the relationship between the degree of polymerization of AP and the inhibitory effects on SEA activities.